Corrugate-film laminate package material and package

ABSTRACT

This invention comprises a corrugated package material wherein the corrugated fluting is attached to one or more sheets of heat shrinkable polymeric film. The heat shrinkable film is preferably on only one side of the corrugated fluting, but may be on both sides of the corrugated fluting. This packaging material is then formed into a carton and this carton filled; or is used to bundle a series of containers, and the final assembly, whether a carton or bundle, heat shrunk, whereby the strength of the corrugate is increased.

[111 3,796,307 [451 Mar. 12,1974

United States Patent McKinney CORRUGATE-FILM LAMINATE PACKAGE XXXXRX9SS9U RUSSMF Umm Av 66 2 4lOO W 22 6 O O U 2 2 m m S .n n "n n .t m Tm nr aswewm flb y tf me H6803! CPBCLD 48 2 667756 999999 llllll 702258 I 1929632 959 20 262730 406255 333323 [22] Filed: June 5, 1972 PrimaryExaminerLeonard Summer [21] Appl. No.: 260,015

Attorney, Agent, or Firm--John J. Toney; William D. Lee, Jr.

Related US. Application Data [62] Division of Ser. No. 7l,063, Sept. 10,1970, Pat. No.

[57] ABSTRACT This invention comprises a corrugated package materialwherein the corrugated fluting is attached to one or more sheets of heatshrinkable polymeric film. The

[52] UISIZZ ITYIQ ..QQQQTLTIEli/fii, 156/84, 161/133,

- 206/819, 229/87 R B65d 65/40, B65d 65/44, 1332b 3/28 heat shrinkablefilm is preferably on only one side of the corrugated fluting, but maybe on both sides of the [5]] Int. Cl..... [58] Field of Search 206/65 S,46 FR; 229/87 R, corrugated fluting. This packaging material is 'then229/DlG. 2, DIG. 12; 161/133; 156/84 formed into a carton and thiscarton filled; or is used to bundle a series of containers, and thefinal assembly, whether a carton or bundle, heat shrunk, whereby thestrength of the corrugate is increased.

[56] References Cited UNITED STATES PATENTS 2,833,404 5/1958 Jacobs etal. 206/65 R 3 Claims, 5 Drawing Figures PATENIEOm 12 mm FIG.

FIG?

CORRUGATE-FILM LAMINATE PACKAGE MATERIAL AND PACKAGE BACKGROUND OF THEINVENTION This invention relates to a corrugated material attached to aheat shrinkable polymeric film, forming a corrugated composite forpackaging. The invention further relates to a package wherein containersare within a carton formed from this corrugated composite; or containersare bundled in this material, and the polymeric film is then shrunk toincrease the strength of the fluting and the final package. Corrugatedcartons are a standard item in commerce for transporting a series ofsmaller containers. These cartons maintain the containers in a setorientation, protect the container surfaces from damage, and givestrength to allow stacking for more efficient storage and transport.Further, corrugated cartons to a degree protect these containers againstmoisture and weather, preserving the more decorative containers withinthe carton. There is a nonending search for cartons which arelight-weight, strong, of low bulk, weather proof, can still maintain thepackaged containers in a set orientation, and are stackable withoutcarton or bundle distortion. The present invention is directed to such apack aging material and package. In the present invention, corrugatedfluting is attached to a heat shrinkable polymeric film. This is theneither formed into a carton or used to bundle a series of containers.When in the form of a carton, it is filled with containers and sealed.In either form, carton or bundle, the package is then heattreated toshrink the polymeric film and tighten the corrugated fluting core. Thisoperation of heatshrinking serves both to tighten the fluting and toplace the package in a state of compression. When stacked, the sides ofthe carton or bundle are not readily placed in a bulging tensioncondition without exerting forces greater than those experienced innormal warehousing. The prior art is illustrated by any of U.S. Pat.Nos. 3,407,987, 3,406,052 and 3,411,689] U.S. Pat. No. 3,407,987 setsout a corrugated packaging material suitable for bundling. U.S. Pat. No.3,406,052 discloses plastic coated corrugated fiberboards and methodsfor making this material. The corrugated flute is here coated on one ortwo sides with the plastic. However, this plastic is not of a shrinkablevariety, and thus is not a similar material, and will not producestackable, nonbulging cartons and bundles. U.S. Pat. No. 3,4l 1,689 setsout a reinforced corrugated paperboard carton material and carton. Inthis instance, a strong non-bulging carton is formed, but it entails theuse of a thermoplastic material for strengthening. Further, forstrength, the container is quite massive. Thick layers of paperboard arenecessary to produce a non-bulging side wall when stacked. The presentinvention provides a low bulk, light-weight packaging material. Whenformed into cartons or bundles, these packages will not bulge when undera force such as in stacking. These packages maintain their shape byhaving a tightened corrugated core, and the carton or bundle is under acompressive force which resists sidewall distortion on stacking.

It is an object of this invention to set out a packaging materialcapable of being formed into a sidewall bulgeresistant carton or bundle.

It is also an object of this invention to disclose a packaging materialwherein corrugated flutes are attached to polymeric heat-shrinkable filmwhich is then formed into a carton or used as a bundling material.

It is further an object of this invention to provide a corrugatedcontainer of high strength, but of a low weight and bulk, and stackablefor storage.

BRIEF SUMMARY OF THE INVENTION Briefly, this invention comprises a newcorrugated packaging material and new cartons and bundled packagesproduced from this material. The corrugated packaging material isconstructed of a corrugated fluting attached to a heat-shrinkablepolymeric film. The polymeric film can be attached to one or both sidesof the corrugated fluting. In use, this material is either formed into acarton or.used to bundle a plurality of containers. This package is thenheated to shrink the polymeric film which tightens the corrugatedfluting, keeping the fluting in a tightened condition and the package ina compressed state. In this condition, forces due to stacking fail tobulge or distort the package, facilitating warehouse storage. I

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of thecorrugated packaging material.

FIG. 2 is an elevation of a single face corrugated packaging material.

FIG. 3 is an elevation of the double face embodiment of the packagingmaterial.

FIG. 4 is an elevation of the corrugated packaging material of FIG. 2with the backing sheet in a shrunken condition.

FIG. 5 is a perspective view of bundled containers.

DETAILED DESCRIPTION OF THE INVENTION More specifically, the preferredembodiments are set out in the accompanying drawings which will now bemore fully discussed. FIG. 1 is a plan view of the packaging material10. This material comprises a heatshrinkable polymeric film layer 11adhesively attached to a paper or paperboard corrugate 12. The polymericfilm in this invention must be of a heat-shrinkable variety. Byheat-shrinkable polymeric film is meant any of the conventionaluniaxially oriented polymeric films which on the application of heat areshrunk to a decreased surface area. Such films comprise orientedpolyolefinic films such as polypropylene, polyethylene,polyisopropylethylene and polyisobutylethylene. Other exemplary filmsare polystyrene, polyethylene terephthalate,polyethylene-2,6-naphthalate, polyethylenel,5-naphthalate,polytetramethylene-1,2- dioxybenzoate, polyhexamethylene adipamide,polyhexamethylene sebacamide, polycaprolaetum, polyvinylchloride andpolymethylmethacrylate. Also included are polymers of alphamono-olefinically unsaturated hydrocarbons with organic compounds havingpolymer producing unsaturation such as is present in butene, vinylacetate, vinyl stearate, vinyl formate,

methyl acrylate, 2-ethyl hexyl acrylate, acrylic acid,

isoprene, butadiene acrylamide, methacrylic acid, ethyl acrylateN-methyl-n-vinyl acetamide and the like. This list is illustrative ofthe types of polymeric films known in the art and is not an exhaustivecitation of heatshrinkable polymeric films. Others are known to the artand exhibit varying degrees of shrink on heating, and are useful in anda part of this invention.

The film in a preferred embodiment is a polyolefin, andpreferablypolypropylene. Polypropylene is readily uniaxially oriented, isdimensionally stable on storage, readily workable for bonding corrugatedfluting, and can be heat-shrunk at moderate temperatures. The thicknessof the film is not critical to the invention, and may range from mils to30 mils.

The corrugated fluting 12 may be of any type and will depend on thesubstance to be packaged and the protection required. The flutingmaterial may be of paper,

paperboard, plastic or a combination of paper and plastic or paperboardand plastic. In a preferred and most useful embodiment, the corrugationis a standard paperboard of A, B or C designation. A-corrugation hasapproximately 36 flutes per foot, B-corrugation has approximately 52flutes per foot, and C-corrugation has approximately 42 flutes per foot.The fluting material may range in thickness from 0.005 inch to 0.02inch, depending on the package requirements. A preferred thickness is0.009 inch. The flutes are either adhesively bonded to the film 11 usinga standard adhesive such as starch or some other special purposeadhesive, or heat sealed, since in many instances the film at elevatedtemperatures has adhesive properties.

FIG. 2 sets out in cross-section a single face corrugated medium. Inthis embodiment, the fluting 12 is bonded to a single sheet of film. Inthis instance, the film is preferably polypropylene. The film thicknessis mil and the corrugate fluting is 0.009 inch thick and contains 36flutes per foot. FIG. 3 sets out in crosssection a double face board.The fluting l2 and film l 1 are the same as in FIG. 2. Film 13 is alsoof a heatshrinkable variety, and may have the same or differing shrinkproperties as film 11.

FIG. 4 sets out in cross-section an exploded view of the corrugatefluting and film of FIG. 2 after heatshrinkage of the film. The film 11,in this instance polypropylene, is heat-shrunk by heating thecorrugate-film composite to 250F to 330F. For other heat-shrinkablepolymer films, the temperature ranges from about 150F to about 350F.These temperatures are those generally encountered, and thisinvention isoperable at other temperatures depending on conditions. For example,shrink tunnel temperatures may be as high as 400F, depending on thethickness of the wrapping, rate of passage through the tunnel and otherfactors. The corrugate core is in this instance in a tightened conditionhaving greater than the original 36 flutes per foot.

FIG. 5 is a perspective view of a plurality of containers bundled withinthe present packaging material, and the polymeric film shrunk, puttingthe corrugate core in a tightened condition and the bundle in acompressed state. The bundle in this embodiment contains tightenedcorrugated fluting on four sides and clear plastic film on the ends.This packaging material may be essentially that of FIG. 1, but with thefilm 11 extending beyond the fluting 12 on each side in the directionlongitudinal with the flutes. This film may be of a uniaxially orbiaxially oriented type, however, in a preferred embodiment when theshrinkable film extends beyond the fluting it should be of a biaxiallyoriented type. By using a biaxially oriented type, not only will thecorrugations be strengthened, but the entire package will bestrengthened. The corrugated fluting may be of the single or double facetype, however, for bundling it is preferably of a single face type; Thewidth of the extension beyond the flutes depends on the package to beformed and may operably be from about 6 inches to about 18 inches ormore. In a further embodiment, in forming a bundle the material of FIG.1 can be used directly where the corrugate composite is cut and foldedand sealed to form a corrugated top and bottom section, or the top andbottom may be left entirely open. The packaging material is useful inany of these embodiments, but packages wherein the top and bottom aresealed are preferred.

The packaging material of FIG. I may also be formed into corrugatedcarton blanks which can then be assembled into cartons. The material inthis instance may be of a single or double face type. The carton whenformed, by heat sealing or adhesives, can be heated to shrink thepolymeric film prior to filling and sealing or after filling andsealing. When in a form to be heated, and the polymeric film shrunkprior to filling and sealing, the material is preferably of the doubleface type.

In a further embodiment of this invention, flat noncorrugated blanks canbe formed at one place and these blanks shipped to the user who, by heatshrinking, forms these blanks into corrugated blanks. In thisembodiment, a uniaxially oriented film is preferably adhesively attachedat set points to a flat fluting type material. The film is preferablyattached to both sides to form a double face material on heat shrinking,although a single sheet of film on one side may be used to form a singleface material. It is usually desirable to precorrugate the flutingmaterial and then flatten it out prior to attaching it to the film toassure an even corrugating without any irregular crinkling duringsubsequent heat shrinking corrugation; Further, in forming the doubleface material, each film is attached at alternating intervals along theflat fluting material so that when the films are heat shrunk, thedecrease in dimension of the film corrugates the flat fluting material.The prime benefitv of such a material is in the volume which must betransported to the user. There is greater efficiency in transporting aflat blank which is then treated to form corrugations, over transportinga corrugated sheet.

The process of heat-shrinking the face film or films is essentially thatof subjecting the film to a temperature wherein by elastic memory thefilm loses its stretched orientation. The heat in this instance can besupplied by radiation, conduction or convection or any combination. Inone technique, the bundles or cartons are conveyed through a tunnelcontaining lamps with a high infrared emission. In another method,warmed air is blown on, and if an unfilled and sealed carton, also in,the carton, shrinking the face films. In general, techniques andequipment for heat shrinking are well known and any of these can beadapted for use with this invention.

As is apparent from FIG. 5, both the corrugate and the bundle are herein a tightened condition. The shrunken film maintains the fluting in atight and defined state, and the entire package in a compressedcondition. Therefore, when stacked and a force is applied to thefluting, the fluting is not deformed in directions parallel ortransverse to the fluting. The shrunken film maintains its tighteningand compressive force on the fluting and package, preventing anysidewall bulging on stacking.

What is claimed is:

l. A package comprising at least one object tightly wrapped in apackaging material comprising a corru- 5 gated substrate having peaksand flutes on each face and a heat shrunk polymeric film attached to thepeaks of at least the outer face of the corrugated substrate,

sively bonded to the peaks of the corrugated substrate.

1. A package comprising at least one object tightly wrapped in a packaging material comprising a corrugated substrate having peaks and flutes on each face and a heat shrunk polymeric film attached to the peaks of at least the outer face of the corrugated substrate, said shrunken film maintaining the fluting and object in a tight, compressed state.
 2. The package of claim 1 wherein said film is heat sealed to the peaks of the corrugated substrate.
 3. The package of claim 1 wherein said film is adhesively bonded to the peaks of the corrugated substrate. 